The present invention relates to a developing apparatus for employing in an electrophotographic apparatus, and more particularly, to a developing apparatus for transporting charged toner by action of an electric field curtain.
Recently, as described in Japanese Laid-open Patent Publication No. 47-47811, Japanese Laid-open Patent Publication No. 59-181371, Japanese Laid-open Patent Publication No. 59-189367, and Japanese Laid-open Patent Publication No. 63-13068, there each have been proposed a developing apparatus for employing in an electrophotographic apparatus in which an electric field curtain developing device is arranged and toner is transported by action of the electric field curtain force to be supplied onto an image-holding member such as a photosensitive drum.
In the apparatus for employing the curtain developing device, however, unless toner is electrically charged ahead of time, the toner cannot be sufficiently and electrically charged and transported by the electric field curtain force. Therefore, the toner can not be promptly and electrically charged, which causes the toner to be scattered and any fog occurs on a copy paper by any poorly charged toner.